Seat shell



FIG. 1 is a front perspective view of the seat shell, showing my new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a side elevation view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof. 

CLAIM The ornamental design for a seat shell, as shown and described. 